Pouring a slab foundation (4x4m) yourself: Is a concrete mixer suitable?

Hello, first of all thanks for all the answers. What would be a good, cost-effective alternative if I want to build a Ytong or KS stone tool shed with 4x4, in which heavy items are to be stored on the floor for longer periods in the future (especially heavy building materials, such as stacked tile packages and roof tiles)? Is there an alternative to a concrete foundation if the shed floor should easily withstand about 150 to 200 kg/m2?

As said, simply compact the ground with gravel and put a small strip foundation on top. You can also mix it in. I don’t see any 20 cm concrete.

I would only make a strip foundation and create the ground with simple paving slabs. Whether the subsoil then needs to be something special is up to you to decide. I can only say that here on site I would simply level the ground with some sand and then lay the slabs directly on top. Then work some sand into the joints and done.

A possible dismantling is then also much easier than if a thick concrete slab would also have to be removed and disposed of.

Ok. So just excavate the soil about 30cm deep, then compact 15-20cm of gravel layer and lay paving slabs on top? Is that sufficient for frost protection and rising moisture from the ground?

And the strip foundation still 80cm deep or would that depth be excessive for a small shed? I mainly planned the depth of the strip foundation + the 20cm floor slab because I had read that this is the minimum standard for protection against ground frost and moisture.

You have already helped me a lot so far, thank you!

You don't need 90 cm deep foundations. 7 cm screed is enough. What's the point of the insulation? Timber frame construction is sufficient for a shed.

The stone-wall choice (insulation) is based on the fact that the garden shed should be low-maintenance (e.g. without needing to be painted, no rotting of wooden components) and stand for the next decades AND I expect this to provide better protection for the contents stored inside (building materials, tiles, possibly even expensive metal tools). That is why I want to ensure now, while I still can, that as little moisture as possible can spread inside the shed and damage the contents.

Ok. So just excavate the ground about 30cm deep, then compact a 15-20cm gravel layer and place paving slabs on top?

Hello I have exactly the opposite opinion. My motto is: More is better. I just did a comparable project: motorcycle garage. 450 x 250 cm. Dug out an 80cm strip foundation. Removed the entire ground 60 cm deep. Filled up with RCL to 30 cm. Laid paving slabs (I still had some, they make a great clean layer) put in plenty of iron. Then filled with concrete. About 4m³. With two friends a good half day of hard work. A few rolls, plenty of malt beer. Now the floor slab is about 25cm thick. That holds. And the revenge: I help my two friends equivalently with their projects. Steven